Preheat the oven to 350°F (175°C) and line a muffin tin with cupcake liners.

In a mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition.

Stir in the buttermilk, vanilla extract, bourbon, and chopped mint leaves.

In another bowl, whisk together the flour, baking powder, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Divide the batter evenly among the cupcake liners.

Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cupcakes to cool completely on a wire rack.

In a mixing bowl, beat the softened butter until creamy.

Gradually add the powdered sugar, mixing on low speed until combined.

Add the heavy cream, mint extract, and bourbon, and beat until fluffy.

If desired, add food coloring to achieve a light green color.

Frost the cooled cupcakes generously with the mint frosting.

Garnish each cupcake with a fresh mint sprig.